Tris-azaaromatic quaternary ammonium salts: Novel templates as antagonists at nicotinic receptors mediating nicotine-evoked dopamine release

A series of tris-azaaromatic quaternary ammonium salts has been synthesized and evaluated for their ability to inhibit neuronal nicotinic acetylcholine receptors (nAChRs) mediating nicotine-evoked ³H]dopamine release from superfused rat striatal slices and for inhibition of ³H]nicotine and ³H]methyllycaconitine binding to whole rat brain membranes. The 3-picolinium compound 1,3,5-tri-{5-1-(3-picolinium)]-pent-1-ynyl}benzene tribromide (tPy3PiB), 3b, exhibited high potency and selectivity for nAChR subtypes mediating nicotine-evoked ³H]dopamine release with an IC₅₀ of 0.2 nM and I_max of 67%.